Abstract:During the trial operation of the feed water pump turbine for a 660MW supercritical unit, problems such as the failing launch, low regulating oil pressure, failing to open quick-closing valve, tripping fault often occurred, which delayed the start time of the unit seriously, affected the safe operation of the unit and the power grid. Combined the oil flow and working principle of feed pump turbine regulating system,this paper analyzed the reasons of failing launch, low regulating oil pressure and so on, and summarized the fault characteristics of the regulating system, put forward the solution ideas and treatment methods, verified the correctness of the treatment method through field test, gave some advises and references for quickly judging and dealing with similar failures of the regulating system as well. At the same time, this paper combined with feed pump turbine quick-closing valve structure principle, derived the force balance equation of moving parts in quick-closing valve, analyzed the influence of quick-closing valve action process on the latching of feed pump turbine and reasons why it cannot be opened normally. Based on the structural principle of the quick closing component, combined with the action process of the quick-closing valve during latching, deduced the reasons of the difference in the rate of oil pressure drop between the success and failure of launch of feed pump turbine , which can provide a basis for the accurate analysis of tripping.